Effects of Structural and Occupant Provision Improvements to the Static and Dynamic Response of the V-22 Osprey Energy Attenuating Troop Seating System

The U.S. Navy has recently undertaken the task of integrating an improved crashworthy troop seat system into the MV-22B and CV-22A tiltrotor aircraft. Although these aircraft currently have crashworthy seating systems installed for cabin occupants, the U.S. Navy desires to upgrade the seat to correct deficiencies found during testing by improving occupant comfort and crashworthiness capability. The baseline seat chosen for integration was an energy-attenuating seat previously qualified for the CH-53D. To meet the design goals for the upgraded seating system, the CH-53D seat was modified with a four point restraint system, new seat pan fabric, addition of foam to the seat pan to reduce occupant fatigue in the lower extremities, and structural design modifications to facilitate interface with the V-22 airframe structure. This paper details the qualification test methodology utilized to substantiate the chosen seat for use in the MV-22B and CV-22A platforms, and describes the results of recent static and dynamic qualification testing. The paper also provides a discussion of structural loads and a comparison of this data to historical test data from the CH-53D program, drawing conclusions on the effects of the seat modifications to the resulting airframe attachment loads, biodynamic loads and required seat stroke distance. It is shown that qualification by similarity back to the CH-53D seat version would be inappropriate given the extent and nature of the seat modifications.